Monday 15 March 1999

Study links pesticides, brain damage

Marla Cone
The Los Angeles Times

Children exposed to pesticides in the womb or at an early age may suffer permanent brain defects that could change their lives by altering behaviour and their ability to do everything from drawing a picture to catching a ball, says new scientific research.

Widely used pest-killing chemicals, in amounts routinely found in farm areas seem able to skew thyroid hormones, which control how the brain of a fetus or young child develops, says the study published in the journal Toxicology and Industrial Health.

Scientists say the study and other recent research support an emerging theory that pesticides may exact a toll on the intelligence, motor skills and personalities of infants, toddlers and preschoolers.

"Data suggest that we may be raising a generation of children with learning disabilities and hyper-aggression," said Wayne Porter, a University of Wisconsin professor of zoology and environmental toxicology.

Mr. Porter's study shows that a common mix of insecticide, herbicide and fertilizer found in drinking water altered the thyroid hormones of young mice.

It also changed their aggressiveness and suppressed their immune systems.

Although a study of mice alone is not overly compelling, the theory is bolstered by recent research on humans.

In tests in Mexico, scientists found striking differences in hand-eye co-ordination and other mental and physical skills when comparing preschoolers in an agrarian region with those in adjacent foothills where no pesticides are used. Four- and five-year-olds in the agrarian area had trouble performing simple motor skills.

They had poorer memory skills and stamina, were more prone to physical aggression and angry outbursts, and were less sociable and creative while playing. Farm and household pest killers are widely used there, and high levels of multiple pesticides have been found in the cord blood of newborns and breast milk of mothers.

Another study found increased birth defects in children conceived during the spring growing season. No one knows what it means for people who consume small traces of the chemicals in their food.

The new hormone studies add to a growing body of research from around the world suggesting that dozens of commonly used pesticides and other chemicals mimic the hormones that control sexual and neurological development.